diff --git a/contentcuration/contentcuration/tests/test_serializers.py b/contentcuration/contentcuration/tests/test_serializers.py
index 2b71c291a6..25331a7daf 100644
--- a/contentcuration/contentcuration/tests/test_serializers.py
+++ b/contentcuration/contentcuration/tests/test_serializers.py
@@ -1,8 +1,8 @@
 from __future__ import absolute_import
 
-from django.core.exceptions import ValidationError
 from django.db.models.query import QuerySet
 from django.test.testcases import SimpleTestCase
+from rest_framework import serializers
 
 from .base import BaseAPITestCase
 from contentcuration.models import Channel
@@ -42,14 +42,14 @@ def test_completion_criteria__valid(self):
         serializer.is_valid()
         try:
             serializer.update({}, serializer.validated_data)
-        except ValidationError:
+        except serializers.ValidationError:
             self.fail("Completion criteria should be valid")
 
     def test_completion_criteria__invalid(self):
         self.data.update(completion_criteria={"model": "time", "threshold": "test"})
         serializer = self.serializer
         serializer.is_valid()
-        with self.assertRaises(ValidationError):
+        with self.assertRaises(serializers.ValidationError):
             serializer.update({}, serializer.validated_data)
 
 
diff --git a/contentcuration/contentcuration/tests/viewsets/test_contentnode.py b/contentcuration/contentcuration/tests/viewsets/test_contentnode.py
index 74f784fdcf..ef2fb9ed4b 100644
--- a/contentcuration/contentcuration/tests/viewsets/test_contentnode.py
+++ b/contentcuration/contentcuration/tests/viewsets/test_contentnode.py
@@ -548,6 +548,22 @@ def test_update_contentnode(self):
             models.ContentNode.objects.get(id=contentnode.id).title, new_title
         )
 
+    def test_cannot_update_contentnode_parent(self):
+        user = testdata.user()
+        contentnode = models.ContentNode.objects.create(**self.contentnode_db_metadata)
+        contentnode2 = models.ContentNode.objects.create(**self.contentnode_db_metadata)
+
+        self.client.force_authenticate(user=user)
+        response = self.client.post(
+            self.sync_url,
+            [generate_update_event(contentnode.id, CONTENTNODE, {"parent": contentnode2.id})],
+            format="json",
+        )
+        self.assertEqual(response.status_code, 400, response.content)
+        self.assertNotEqual(
+            models.ContentNode.objects.get(id=contentnode.id).parent_id, contentnode2.id
+        )
+
     def test_cannot_update_contentnode(self):
         user = testdata.user()
         channel = testdata.channel()
@@ -742,6 +758,40 @@ def test_update_contentnode_update_options_completion_criteria_threshold_only(se
         self.assertEqual(c.extra_fields["options"]["completion_criteria"]["model"], completion_criteria.TIME)
         self.assertEqual(c.extra_fields["options"]["completion_criteria"]["threshold"], 10)
 
+    def test_update_contentnode_update_options_invalid_completion_criteria(self):
+        user = testdata.user()
+        metadata = self.contentnode_db_metadata
+        metadata["extra_fields"] = {
+            "options": {
+                "completion_criteria": {
+                    "model": completion_criteria.REFERENCE,
+                    "threshold": None,
+                }
+            },
+        }
+        contentnode = models.ContentNode.objects.create(**metadata)
+        self.client.force_authenticate(user=user)
+        # Change extra_fields.options.completion_criteria.model
+        # and extra_fields.options.completion_criteria.threshold
+        response = self.client.post(
+            self.sync_url,
+            [
+                generate_update_event(
+                    contentnode.id,
+                    CONTENTNODE,
+                    {
+                        "extra_fields.options.completion_criteria.model": completion_criteria.TIME,
+                    }
+                )
+            ],
+            format="json",
+        )
+        self.assertEqual(response.status_code, 400, response.content)
+        c = models.ContentNode.objects.get(id=contentnode.id)
+
+        self.assertEqual(c.extra_fields["options"]["completion_criteria"]["model"], completion_criteria.REFERENCE)
+        self.assertEqual(c.extra_fields["options"]["completion_criteria"]["threshold"], None)
+
     def test_update_contentnode_add_multiple_metadata_labels(self):
         user = testdata.user()
 
diff --git a/contentcuration/contentcuration/viewsets/contentnode.py b/contentcuration/contentcuration/viewsets/contentnode.py
index 79676716a5..c7bb2e222a 100644
--- a/contentcuration/contentcuration/viewsets/contentnode.py
+++ b/contentcuration/contentcuration/viewsets/contentnode.py
@@ -3,6 +3,7 @@
 from functools import reduce
 
 from django.conf import settings
+from django.core.exceptions import ValidationError as DjangoValidationError
 from django.db import IntegrityError
 from django.db import models
 from django.db.models import Exists
@@ -273,7 +274,10 @@ class CompletionCriteriaSerializer(JSONFieldDictSerializer):
 
     def update(self, instance, validated_data):
         instance = super(CompletionCriteriaSerializer, self).update(instance, validated_data)
-        completion_criteria_validator.validate(instance)
+        try:
+            completion_criteria_validator.validate(instance)
+        except DjangoValidationError as e:
+            raise ValidationError(e)
         return instance